SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '546b87dc3571aba27b79f069172b435507aaebdb87354df6b0c3e5f6fafb5166' 
  AND token = '8BIOrlghhaVe/s6qGoJ1Z5jth3Lv35Un72PqPkQn/+w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}